This invention relates to a cleaning apparatus for an electrostatographic reproducing machine. The cleaning apparatus utilizes vibratory energy to obtain improved cleaning of the imaging surface of the machine. In particular, this invention is directed to the use of ultrasonic vibrations coupled through an air gap to the imaging surface for removing the residual material. Alternatively, conventional mechanical cleaning is augmented by simultaneously applying vibratory energy from the back of the imaging surface at the cleaning station.
Classical cleaning systems utilized in electrostatographic reproducing machine, for example, use fiber brushes, reverse development, elastomeric blades, webs, etc. These approaches require a strong mechanical coupling between the photoreceptor surface being cleaned and the cleaning device. This can ultimately lead to undesirable effects such as photoreceptor filming or abrasion. Various contactless pneumatic cleaning systems are also known in the art. For example, in U.S. application Ser. No. 552,392, now U.S. Pat. No. 4,026,701 to Till et al, a gas impingement and suction cleaning system is described wherein a gas under pressure is applied to a photosensitive surface to dislodge toner particles thereon and a suction source is utilized to collect and transport away the dislodged toner. Another form of pneumatic cleaning system is described in U.S. application Ser. No. 717,953, now abandoned, filed of even date herewith to Lindblad et al. In the latter system suction alone is utilized to dislodge and collect toner particles from the surface of a photosensitive member. Other pneumatic cleaning systems are described in U.S. Pat. Nos. 3,420,710 to Wollman; 3,615,813 to Clarke; 3,645,618 to Lancia; 3,688,008 to Severynse; 3,741,157 to Krause; and 3,743,540 to Hudson. The Wollman patent shows exposing a web with electrostatically adhering particles thereon to a shock wave created by air directed at at least sonic velocity to dislodge the particles which are carried away at reduced pressure.
It is also known to employ ultrasonic vibratory energy to provide cleaning in electrostatographic reproducing machines. In U.S. Pat. No. 3,483,034 to Ensminger, ultrasonic energy is utilized to remove toner from a photoreceptor surface by employing a liquid coupling between an ultrasonic transducer and the surface. Similarly, Defensive Publication T893001 to Fisler discloses ultrasonic cleaning of a xerographic element utilizing a liquid coupling. When utilizing a liquid coupling cavitation in the liquid occurs under the influence of the ultrasonic vibrations imparted thereto. A cavitation type reaction can cause deleterious effects such as photoreceptor abrasion or damage. Reference is also had to U.S. Pat. Nos. 3,422,479 to Jeffee and 3,635,762 to Ott et al, which show the use of ultrasonic cleaning of film-type webs. In accordance with the present invention an air coupling is provided between the vibratory source and the imaging surface. This is beneficial in reducing damage to the imaging surface while providing good cleaning.
In U.S. Pat. No. 3,617,123 to Emerson, a method and apparatus for cleaning residual toner material is provided wherein a brush is mounted at the entrance to a development-cleaning station and is vibrated to uniformly distribute residual toner over the entire area of the photoconductive surface to improve cleaning. The brush itself does not remove the toner.
In U.S. patent application Ser. No. 547,522, filed Feb. 2, 1975, to Meltzer, a blade cleaning system for an electrostatic reproducing machine is described wherein the blade is rapidly vibrated in a direction parallel to the imaging surface. U.S. patent application Ser. No. 547,523 to Stange, filed Feb. 6, 1975, now U.S. Pat. No. 4,007,982, is also directed to a blade cleaning apparatus for an electrostatographic reproducing machine, however, the blade edge is vibrated at ultrasonic frequencies in a direction parallel to the imaging surface so as to reduce the frictional engagement between the blade and the imaging surface. In these blade cleaning systems there is a mechanical engagement between the vibrating blade edge and the imaging surface.